Friday, August 31, 2012

In praise of LCA thinking

I heartily commend to all environmental engineers (including fellow auspicious poop engineers!) the subject of Life Cycle Assessment (LCA), for several reasons:

It makes you think holistically. It's easy to be miopically focused on one environmental impact - hypoxia, eutrophication, carbon footprint, acid rain, etc. - but an LCA makes you consider all potential impacts. I offer the crass example of focusing solely on carbon footprint for wastewater treatment... the lowest CF for sewage treatment is no treatment and just let the sewage go into the river, lake or estuary! Of course this causes untold environmental and health impacts.

It makes you think globally. It's easy to look at your own litte corner of a village, town, city, state, or country, but, in our global economy an LCA expands your considerations to a global perspective. In a recent LCA we did, for example, we considered the impact of using methanol. In digging into the data we discovered that our methanol came from Trinidad who are using their significant natural gas reserves to produce higher value products such as methanol. Who'd have thought?!

It makes you think systematically. Your treatment plant is one cog in a huge anthropogenic and environmental system. An LCA makes you think about wider environmental impacts and maybe the solution to reducing environmental impacts lies outside of the boundaries of your own system. In wastewater the example I like is that water conservation (i.e. using less water in your home and in industries) has a significant impact on the quantity of wastewater that has to be treated, but also reduces the energy needed to pump it, the pipes needed to convey it and the energy used in a home to heat it... the chemicals needed to treat it, the water stress from abstracting it, the land needed to dam it and use it... shall I go on? But wait, I'm just a poop engineer looking at the wastewater end right? Hmm. Thinking.

It makes you think about sources. In a very recent project we did an LCA that included glycerine use. Our glycerine is sourced as a byproduct of soy bean processing for biofuels. Inadvertently we put glycerine sourced from Brazil in our model and it showed a very high carbon footprint due to land clearance in the Amazon. Bad. Oh wait, our byproduct is actually from the US where we don't need to clear rainforest to produce soy beans. We selected the US beans and now we have a net carbon reduction due to carbon sequestration for this part of the model. I guess "buy local" is the key! (Unless you live in Brazil... think about it!)

It makes you think. Environmental science and engineering are fascinating and complex issues. LCA makes me stop and think. I was trained as a chemical engineer and throughout my career I've been a process modeler which means I have an appreciation for mass and energy balances. LCA has several definitions, but it's basically the mother of all mass and energy balances! Sure it's imperfect and in many areas it uses crude approximations, but hey, it makes you think, holistically, globally and systematically!

So, to all my fellow environmental engineers, I heartily encourage you to get into LCA. We use SimaPro, which is great, but there are several decent software packages out there to help you including a free one.

About Me

A wastewater engineer since the early 90's, originally from the UK, now living in Kansas with a brief but wonderful interlude in Western Australia. Interested in sustainability, water issues, process modeling and online instrumentation. Also interested in social media and most things vaguely geeky.